Brian over at BTG Audio, I've had him do previous work for me so it was natural to go back to him. We went over a few different cable plans to see what would be best in the long run and the resulting cable was the most universal while being cost effective (was toying around with mini-XLR and other type stuff, but went standard instead). Great guy to work with. He's recabled and modded some headphones in the past for me and his work has been phenomenal.

I actually contemplated getting the 125wpc Emotiva instead of the 50wpc, but ultimately I think the 50wpc with the volume knob is going to be the way to go for the HE-500.

Next up I want to see about a DAC that synergizes really well with the whole affair. Gonna try a NFB12, E10, MusicStreamerII and a few others to see if there's any noticeable difference, may buy something else too just to see how it all works together and find what sounds best to my ears. I like the NFB12, but it's DAC is the same as the E10 so it sort of renders it pointless, but the NFB12 has more connectivity for other devices, but in general I use USB mostly anyways. Not sure if the music streamer ii is an upgrade or sounds different from the NFB12 or E10 frankly. Guess I'll find out the expensive way. Open to suggestions of course on a new DAC (down grade, side grade ,up grade, doesn't matter to me) from anyone who's familiar with the HE-500 and relatively warm/neutral amps.

The 125w puppies would for sure be too much. The 500s top out for power pretty quickly compared to the black hole 6s. The thing that speaker amps offer that is harder to find in headphone amps are the soundstage gets bigger with better placement and the bass impact is harder. Both of those benefit the 500s.

DACs are a different beast but is certainly personal taste dependent. The orthos can take a SS DAC feed well because of their smoother presentation. But don't discount an older DAC either. For value, you can get some outstanding performers. With the advent of USB to S/Pdif converters, new life has been injected in the older quality DACs. JMO, if you are going to use the better performance of a SS amp, consider a tube DAC. Like everything, budget will steer you to more specific recommendations.

The 125w puppies would for sure be too much. The 500s top out for power pretty quickly compared to the black hole 6s. The thing that speaker amps offer that is harder to find in headphone amps are the soundstage gets bigger with better placement and the bass impact is harder. Both of those benefit the 500s.
DACs are a different beast but is certainly personal taste dependent. The orthos can take a SS DAC feed well because of their smoother presentation. But don't discount an older DAC either. For value, you can get some outstanding performers. With the advent of USB to S/Pdif converters, new life has been injected in the older quality DACs. JMO, if you are going to use the better performance of a SS amp, consider a tube DAC. Like everything, budget will steer you to more specific recommendations.

Would actually love recommendations on a DAC, especially a tube DAC as I've not toyed around with that. Budget wise, not really sure. I'm trying to keep it rather value oriented, since I've already wasted tons of money on things like Lyr+Bifrost and found that a simple NFB12 does the same job, and now a new cable and Emotiva amp for the HE-500, makes me want to try various DAC's in the $50~200 range roughly, but again, I have no real limit. I just don't want to spend another $900 on a setup that basically a $200 thing can do. But I'm open to ideas even if they're pricey and I'm always open to used gear as I prefer to buy things second hand if I can get a good enough discount to warrant it. I also like things that have good re-sale ability, so I stay away from novelty things that no one really will buy again.

I tried using my Firstwatt F5, which is 25 watts into 8ohms, using the Burson Soloist as preamp, and going into my LCD3.

It sounded great, BUT there was a noise problem that I couldn't live with. Could be heard in quiet passages, and was very obvious with no music playing.

I think it needs resistors to be quiet.

Look forward to trying the HE6 with the same amp setup.

Had the same problem going from J2 to HD800, depending on what I was using for the DAC and preamp. Definitely requires some experimentation. I forgot which combination I had to use to get rid of the noise, but it eventually went away. The HE6 never had noise problems for me, but I've found orthos more forgiving about noisy amping.

Are you using an authentic F5 or a clone? The clones tend to suffer from more noise issues than amps from Nelson Pass' kitchen table.

I suggest using a volt meter and look for any DC voltage on the speaker taps prior to using your expensive headphone there. If you have used these speaker taps with actual speakers and have not heard distortion you are probably ok, but measuring for DC voltage is the only true way to ensure the drivers are not going to deform badly and possibly damage. It is all about how confident you are about the speaker taps only having AC voltage on them.